SilverWook said:

... a recreation of the long defunct GP rating card, (THX's original rating, believe it or not) ...

Now there's something to add to a THX 1138 Theatrical Restoration -- if only we knew what the theatrical release looked like. Maybe that GP rating is a clue?

Wikipedia said:

Motion Picture Association of America film rating system
...
The ratings used from 1968 to 1969 were:
    Rated G: General Audiences – Suggested for General Audiences (All Ages Admitted)
    Rated M: Mature Audiences – Suggested for Mature Audiences (Parental Discretion Advised)
    Rated R: Restricted – Persons Under 16 Not Admitted Unless Accompanied by Parent or Adult Guardian
    Rated X: Adults Only – Persons Under 18 Will Not Be Admitted
...
From M to GP to PG
Many parents were confused by the "M" and "R" ratings, thinking that the former was the "sterner" rating. In 1970, "M" was renamed to "GP" (intended to indicate "General audiences, Parental guidance suggested"), then revised in 1972 to "PG".

Could the early TV broadcasts -- with cuts & zooms to minimize Lucas porn -- be the General,Parental (GP) theatrical release? Georgie ... you naughty boy ...